/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jena.arq.querybuilder.rewriters;

import java.util.Iterator;
import java.util.Map;
import java.util.Objects;

import org.apache.jena.arq.querybuilder.AbstractQueryBuilder;
import org.apache.jena.graph.Node;
import org.apache.jena.graph.Triple;
import org.apache.jena.query.Query;
import org.apache.jena.sparql.core.TriplePath;
import org.apache.jena.sparql.core.Var;
import org.apache.jena.sparql.engine.binding.Binding;
import org.apache.jena.sparql.syntax.*;

/**
 * A rewriter that implements an ElementVisitor
 *
 */
public class ElementRewriter extends AbstractRewriter<Element> implements ElementVisitor {

    /**
     * Constructor
     *
     * @param values The values to rewrite with.
     */
    public ElementRewriter(Map<Var, Node> values) {
        super(values);
    }

    @Override
    public void visit(ElementTriplesBlock el) {
        ElementTriplesBlock newBlock = new ElementTriplesBlock();
        Iterator<Triple> tIter = el.patternElts();
        while (tIter.hasNext()) {
            newBlock.addTriple(rewrite(tIter.next()));
        }
        push(newBlock);
    }

    @Override
    public void visit(ElementPathBlock el) {
        ElementPathBlock newBlock = new ElementPathBlock();
        Iterator<TriplePath> tIter = el.patternElts();
        while (tIter.hasNext()) {
            newBlock.addTriplePath(rewrite(tIter.next()));
        }
        push(newBlock);
    }

    @Override
    public void visit(ElementFilter el) {
        ExprRewriter exprRewriter = new ExprRewriter(values);
        el.getExpr().visit(exprRewriter);
        push(new ElementFilter(exprRewriter.getResult()));
    }

    @Override
    public void visit(ElementAssign el) {
        Node n = changeNode(el.getVar());
        if (n.equals(el.getVar())) {
            ExprRewriter exprRewriter = new ExprRewriter(values);
            el.getExpr().visit(exprRewriter);
            push(new ElementAssign(el.getVar(), exprRewriter.getResult()));
        } else {
            // push( new ElementAssign( el.getVar(), NodeValue.makeNode( n )) );
            // no op
            push(new ElementTriplesBlock());
        }

    }

    @Override
    public void visit(ElementBind el) {
        Node n = changeNode(el.getVar());
        if (n.equals(el.getVar())) {
            ExprRewriter exprRewriter = new ExprRewriter(values);
            el.getExpr().visit(exprRewriter);
            push(new ElementBind(el.getVar(), exprRewriter.getResult()));
        } else {
            // push( new ElementBind( el.getVar(), NodeValue.makeNode( n )) );
            // no op
            push(new ElementTriplesBlock());
        }
    }

    @Override
    public void visit(ElementUnfold el) {
        Node n1 = changeNode(el.getVar1());
        Node n2 = changeNode(el.getVar2());
        if ( Objects.equals(n1, el.getVar1()) && Objects.equals(n2, el.getVar2()) ) {
            ExprRewriter exprRewriter = new ExprRewriter(values);
            el.getExpr().visit(exprRewriter);
            push( new ElementUnfold(exprRewriter.getResult(), el.getVar1(), el.getVar2()) );
        } else {
            // push( new ElementBind( el.getVar(), NodeValue.makeNode( n )) );
            // no op
            push(new ElementTriplesBlock());
        }
    }

    @Override
    public void visit(ElementData el) {
        ElementData retval = new ElementData();
        for (Var v : el.getVars()) {
            retval.add(v);
        }
        for (Binding binding : el.getRows()) {
            retval.add(binding);
        }
        push(retval);

    }

    @Override
    public void visit(ElementUnion el) {
        ElementUnion retval = new ElementUnion();
        for (Element e : el.getElements()) {
            e.visit(this);
            retval.addElement(getResult());
        }
        push(retval);
    }

    @Override
    public void visit(ElementLateral el) {
        el.getLateralElement().visit(this);
        push(new ElementLateral(getResult()));
    }

    @Override
    public void visit(ElementSemiJoin el) {
        el.getSubElement().visit(this);
        push(new ElementSemiJoin(getResult()));
    }

    @Override
    public void visit(ElementAntiJoin el) {
        el.getSubElement().visit(this);
        push(new ElementAntiJoin(getResult()));
    }

    @Override
    public void visit(ElementOptional el) {
        el.getOptionalElement().visit(this);
        push(new ElementOptional(getResult()));
    }

    @Override
    public void visit(ElementGroup el) {
        ElementGroup retval = new ElementGroup();
        for (Element e : el.getElements()) {
            e.visit(this);
            retval.addElement(getResult());
        }
        push(retval);
    }

    @Override
    public void visit(ElementDataset el) {
        Element pattern = null;
        if (el.getElement() != null) {
            el.getElement().visit(this);
            pattern = getResult();
        }
        push(new ElementDataset(el.getDataset(), pattern));
    }

    @Override
    public void visit(ElementNamedGraph el) {
        Node n = el.getGraphNameNode();
        if (n != null) {
            n = changeNode(n);
        }
        el.getElement().visit(this);
        push(new ElementNamedGraph(n, getResult()));
    }

    @Override
    public void visit(ElementExists el) {
        el.getElement().visit(this);
        push(new ElementExists(getResult()));
    }

    @Override
    public void visit(ElementNotExists el) {
        el.getElement().visit(this);
        push(new ElementNotExists(getResult()));
    }

    @Override
    public void visit(ElementMinus el) {
        el.getMinusElement().visit(this);
        push(new ElementMinus(getResult()));
    }

    @Override
    public void visit(ElementService el) {
        el.getElement().visit(this);
        push(new ElementService(changeNode(el.getServiceNode()), getResult(), el.getSilent()));
    }

    @Override
    public void visit(ElementSubQuery el) {
        Query q = AbstractQueryBuilder.clone(el.getQuery());
        push(new ElementSubQuery(AbstractQueryBuilder.rewrite(q, values)));
    }

}
